At the age of 76, longtime farmer Will Allen is still looking for ways to diversify a 40-acre operation that already includes everything from pick-your-own pumpkins to a field-side café.

So when Vermont lawmakers last month gave final approval to a bill that would legalize the cultivation of hemp, Allen began contemplating ways to introduce the crop to his Cedar Circle Farm in East Thetford.

“You can grow it for food, for fuel, for fiber,” Allen said recently. “There’s already a proven market for hemp locally, and there’s no reason for us not to be growing it here.”

It’s been nearly 60 years since the federal government uprooted the nation’s once-thriving hemp industry. Though hemp contains only trace levels of THC — an active ingredient in marijuana — its genetic similarities to its psychotropic cousin have landed it alongside heroin and LSD on the list of “Schedule I” narcotics banned by the federal government.

Vermont’s new legislation, signed into law Monday by Gov. Peter Shumlin, won’t alter federal statutes. And despite the pro-hemp efforts of lawmakers including Rep. Peter Welch, Congress doesn’t look poised to end the hemp ban.

But with local law enforcement authorities out of the way, farmers like Allen may decide that the benefits outweigh the still considerable risk of introducing to their fields a crop that hasn’t been harvested here since shortly after World War II.

“It gives farmers that additional crop in the rotation that can benefit the farm income,” said Robb Kidd, an organizer at Rural Vermont, the Montpelier-based nonprofit that helped shepherd the legislation through the Statehouse. “It doesn’t require pesticides or herbicides, it does well in marginal soils, and it’s a quick-growing crop, so there are lots of reasons why farmers would want to grow it.”

Kidd said he expects only a few farmers to roll the dice. Federal authorities would most likely only eradicate the plot, rather than prosecute the farmer, as has been general practice in the handful of other states that have legalized hemp. But penalties for getting caught with a field full of the crop could land a grower in federal prison for decades.

Allen says the threat of land seizure is of far greater concern to him than potential jail time. That’s why he’s in the market for a small plot of land near his existing farm, a transaction he’d complete using a consortium or other entity legally distinct from both Cedar Circle and himself.

Allen was arrested in 2010 when he and other demonstrators took spades to the lawn of the DEA headquarters in Washington, D.C., and planted hemp seeds.

“I’m not afraid of jail,” Allen said. “I do not want to lose the farm.”

Shumlin said Monday he signed the legislation “because I believe the growing of hemp should be legal.”

“Hemp, a different variety of the same plant that produces marijuana, is not a drug but instead a crop with many constructive uses,” Shumlin said.

He said, however, that he has “concerns about the details of this bill.”

Federal legislation, Shumlin said in a statement, means “farmers who choose to grow hemp do so at their own risk and need to be aware of the possible consequences.”

Shumlin is also concerned about how the law might affect the prosecution of felony marijuana cases in the state. The legislation changes the definition of marijuana in Vermont from cannabis sativa containing any THC to cannabis sativa containing THC of concentrations in excess of 0.3 percent.

That means state forensics labs must now confirm not just the existence of THC in a plant, but a percent content, a requirement that could, according to law enforcement officials, add costs and complexity to prosecutions.

“Although I strongly support the principle behind this law,” Shumlin said in his statement, “I will ask my administration to carefully watch its implementation and to work with legislators to correct any deficiencies.”

The legislation replaces an earlier law that legalized hemp here but prohibited Vermont farmers from cultivating it until federal policy changed.

Netaka White, bioenergy program director at the Vermont Sustainable Jobs Fund, said the state’s farmers have a legitimate economic interest in seeing hemp become part of the agriculture mix. Based on data from Canada, where farmers harvest more than 50,000 acres of hemp annually, White said Vermonters could expect to see net yields of $250 to $500 per acre, as much or more than conventional crops.

The retail market for hemp products in the United States — driven by demand for the oil, protein, textiles and fuel derived from the plant — is closing in on $500 million annually.

“There is no hallucinogenic or drug value, but there is fiber value, fuel value and food value,” White said.

White said the crop lends itself to the “value added” trend that has helped buoy small farms in Vermont. Investments in a seed oil press, White said, could allow a farmer to multiply per-acre revenues.

“Is it going to become a cash crop for Vermont overnight? Not yet. Federal law still has to change,” White said. “But as soon as it does, the floodgates are going to open, and we’re going to figure out new markets for it.”

Kidd, at Rural Vermont, said the state’s trailblazing legislation will keep farmers here on the leading edge of the coming hemp boom. The handful of farmers willing to take the risk, he said, will be able to impart their knowledge to fellow farmers. He said those farmers will also be able to begin developing seed stock, a challenge given that importation of hemp seeds across the U.S. border with Canada remains a felony.

The growing season is too far along now for anyone to begin growing hemp in Vermont this year. But Kidd expects to see at least a couple “test plots” next spring.

“A lot of farmers are very interested in growing it,” Kidd said. “There are going to be challenges early on, but we see this eventually being an important part of the mix for many Vermont farmers.”